S1PR1 and vitiligo: Recently the resident memory T (TRM) cells in vitiligo, one of the current research interest, is at the emerging stage.[5,6] TRM cells marked by the expression of surface markers CD69 and CD103 are responsible for the recurrence of many autoimmune diseases.[7] CD69 is the hallmark to define TRM in tissues through downregulation of surface expression of sphingosine 1 phosphate receptor 1.